August bernhardt drautz



(No Model.)

A B. DRAUTZ.

GOMPOUND ENGINE.

No. 422,051. Patented Feb. 25, 1890.

UNITED ySTATES PATENT OFFICE.

AUGUST BERNHARDT DRAUTZ, OF STUTTGART, VURTEMBERG, GERMANY.

COMPOUND ENGINE.

SPECIFICATION forming part of Letters Patent No. 422,051, dated February25, 1890.

Application iiled March 19, 1889. Serial No. 303,860. (No model.)Patented in England March 1, 1889, No. 3,6131

To @ZZ whom it may concern.-

Beit known that I, AUGUST BERNHARDT DRAUTZ, a subject of the Emperor ofGermany, and a resident of Stuttgart, Viirtemberg, Germany, haveinvented a new and useful Improvement in Compound Engines, (for which Ihave obtained patent in England dated March 1, 1889, No. 3,613,) ofwhich the `following is a specification.

This invention relates to an improved compound engine, and has for itspurpose to more completely utilize the motive power than is the case inthe compound engines hitherto known. The improved engine has two pistonsof different cross-sections and only one distribution-canal.

Referring to the accompanying drawings, Figure 1 is a longitudinalsection showing the position of the double piston when thedistribution-canal is open; Fig. 2, a longitudinal section showing theposition of the piston when the said canal is closed; and Fig. 3 is alongitudinal section of the improved device as applied to percussionboring-machines. y

The pistons A and A of different crosssection are connected with eachother by means of the rod a, the diameter of which is inferior to thatof the small piston A the piston-rod a passing through the rearcylinder-cover. The pistons operate in the cylinders B and B',communicating with one another through the distribution-canal h, oneaperture of which terminates about t-he middle of the small cylinder B',and at the end of the return-stroke of the double piston, Fig. 2,communicates with the inlet G for the fresh motive power, (steam orair,) while at the end of the forward stroke, Fig. l, it is situatedbetween the two pistons. The other aperture of the distribution-canalterminates in the 'large cylinder B at the rear end thereof, and

difference of cross-sections referred to, forces the doublepiston'forward, as indicated by an arrow, notwithstanding the constantcounter-pressure on the piston A produced by the entering motive power.The volume of the :distribution-canal must of course be so chosen as toenable the pressure on the rear surface of the piston A to overcome theaforementioned counter-pressure throughout the whole stroke. As soon asthe piston A has closed the one aperture of' the canal h, the motivepower inclosed in h and B expands until the piston A has passed andreopened the said aperture, Fig. 1. On the piston A attaining theposition shown in Fig. 1 a communication is established between the twohalves oit' the cylinder B through the canal h, as the rod a has across-section inferior to that of the cylinder B. The already-expandedmotive power therefore is allowed to be distributed on the two surfacesof the piston A, thus producing a compensation of pressure with regardto the latter. Subsequently the constant pressure of the fresh motivepower on the outer surface of A returns the double piston, as indicatedin Fig. 1 by an arrow. Thereby first one aperture of thedistribution-canal is closed by A and a further expansion takes placewithin the cylinder-spaces comprised between the pistons, whilecompression is produced in the canal 7L and in the rear space of thecylinder B. This second period of expansion, taking place on theopposite side of the first, terminates with the opening of theexhaust-canal I by the piston A, while simultaneously the compressionceases with the opening of one aperture of the canal 7L by the pistonA'. The double piston having resumed the position shown in Fig. 2, theabove operation is repeated..

The modification (shown by Fig. 3) of the improved system is intended tobe applied to percussion boring-machines to allow the utilized motivepower to be employed for removing the bore-dust. For this purpose thepiston-rod d, connected with a hollow boringtool, is likewise madehollow and connected by means of small apertures t' with thecylinder-spaces comprised between the pistons A and A. With thismodication a second period of expansion between the pistons A and A doesnot take place; but the utilized motive power fiows from the rear halfof` the cylinder B through canal 7L and apertures i provided in thepiston A into the hollow piston-rod a', whence it passes to theboringtool and bore-hole, delivering the latter of the bore-dust. Inthis modification the exhaustcanal I is replaced by the hollowpiston-rod a.

What I claim is- 1. A compound motor actuated by gaseous fluid7 havingtwo pistons A and A of different cross-sections, connected by a rod a ofa cross-section inferior to that of the small piston, and atransmission-port 71 so connecting the cylinders B and B as to cause themotive force to act during the forward stroke of the two pistons withfull pressure on the small piston A', while during the reverse movementof the pistons expansion takes place von one side of the large piston,and during t-he next forward stroke a sec'ond expansion of the motivefluid already expanded is produced on the other side of the large pistonfor the purpose of completely utilizing the motive force, substantiallyas specified.

2. A motor for rock-drilling purposes actuated by gaseous fluid, havingtwo pistons A and A of different cross-sections connected by a rod a ofa cross-section inferior to that of the small piston, the large piston Ahaving apertures t' and so communicating with its hollow piston-rod aand transmission-port h as'to cause the waste motive fluid to passthrough the piston-rod a and be utilized for removing bore-dust from aboring-tool connected therewith, substantially as specified.

In testimony whereof I have signed this specification in the presence oftwo subscribing witnesses.

' AUGUS'ILBERNI'IARDT DRAUTZ. Witnesses:

HERMAN PAHL, ADoLla` RAMsPERGER.

